Because a majority of cancers originate in the epithelium, the development of a minimally invasive laser therapy endoscope is proposed for the treatment of early cancer and precancerous lesions. During treatment for bladder cancer, many early cancers go undiagnosed, resulting in the highest recurrence rate of any cancer. A new scanning fiber endoscope will be developed for integrated laser imaging, early tumor identification, staging, and treatment, using topically applied photosensitizer dyes. To provide accurate control of the laser treatment, the same micro-optical fiber scanner is used for both in vivo imaging and laser therapy. This dual functionality will insure pixel-accurate delivery of the high-intensity laser light. The fiber scanner is located at the distal tip of an ultrathin (1.2 mm outer diameter) and flexible endoscope. Initial testing will be conducted on living artificial tissue models and a rat bladder cancer model that have been seeded with cancer cells from culture. The resulting superficial tumors within the epithelium will be destroyed using fluorescence image-guided laser therapy at single pixel accuracy. Performance evaluations of two therapeutic laser wavelengths and optical cancer indicators will be used to choose the most effective system, taking into account efficiency and safety. All systems under testing will have a high performance versus low clinical cost in practice. Furthermore, there is broad application of this technology to earlier treatments among lung, colorectal, esophageal, pancreatic, and bile duct cancers. Due to the reduced length of this project there will be no development of an interactive computer interface that estimates dosimetry of the image-guided intervention under real-time feedback control for the purpose of minimizing collateral damage to the tissue.